What is the logic of marbles in medium practice section…how it can be (n-1)C(k-1)??..pls help…thanks

There are many duplicates questions related to question please see this post .

http://discuss.codechef.com/questions/38041/medium-level-problem-marbles-sigsegv-error.

Hope this will help.

Thanks .

Just two days back even i was wondering the same… when i found this

and please go through Wikipedia. It contains detailed explanation.

It’ll surely help…!!!

Reali thanks…this qstion was disturbing me for two days…

You can use the popular Beggar’s method (is usually taught in High Schools).

Distribution of n-k coins to k beggars.

For distribution of r identical coins among n beggars is c(n+r-1,r-1)

Applying the formula you get required the formula

Why is the return value for nCk a double?

sorry about that. But its not working with long long int also

https://www.codechef.com/viewsolution/30681172

do i need to change my logic or a minor change in this code would work?

I mean there are 2 ways.

https://www.codechef.com/viewsolution/30683459

https://www.codechef.com/viewsolution/30683586

Got it. Thanks a lot.

when we want to select remaining n-k coins from infinite coins then (n-r+1)Cr would be used. In this formula n would be (infinity-k) and r would be (n-k). PLEASE help where am i wrong